Machine for test smoking cigarettes



Aug. '12, 1969 P. s. PARKS MACHINE FOR TEST SMOKING CIGARETTES 2 Sheets-Sheet 1 Filed Jan. 4, 1967 Aug. 12, 1969 P. s. PARKS 3,450,374

' MACHINE FOR TEST SMOKING CIGARETTES Filed ban. 4, 19a? 2 Sheets-Sheet 2 MACHINE FOR TEST SMQKING CIGARETTES Philip S. Parks, Richmond, Va., assignor to Philip Morris,

Incorporated, New York, N.Y., a corporation of Virginia Filed Ian. 4, 1967, Ser. No. 607,234 Int. CI. 80111 31/00 US. Cl. 73-23 11 Claims ABSTRACT OF THE DISCLGSURE A machine for pulling cigarettes at regular intervals with a piston pump unit, the stroke of which is adjustable to allow for puffing varying volumes of smoke. The pump piston is stroked with a reversible electric motor coupled thereto through a rack and pinion unit, the arrangement being such that the rack is fixed and the pinion, which is mounted in a coupling bracket, bodily reciprocates along with the bracket, piston and motor. An electric control circuit controls pump operation utilizing limit switches actuated at the ends of stroke travel of the pump piston to reverse motor rotation in corresponding directions, a circuit resistance being used to slow motor speed during the pump discharge stroke to a lesser value than the speed during the intake stroke. A multi-p-orted solenoid valve controls smoke flow from the cigarette to the pump and from the pump to a smoke analyzer unit, opening and closing of the respective ports recurring automatically in correspondence to the direction in which the drive motor is rotating. A hydraulic damping unit is coupled with the pump piston and operates in tandem therewith to absorb piston inertia during pump discharge of the smoke, a smoke analyzer unit used in conjunction with the machine and maintained under vacuum.

Background of the invention Test smoking of cigarettes is a standard practice in the tobacco industry and is employed, inter alia, to provide quantitative and qualitative data for measuring uniformity and consistency of product quality. Additionally, test smoking of cigarettes is carried out as part of continuing research and development activities directed toward producing improved, more effective cigarette filter elements as well as procedures for treating smoking tobacco to reduce or remove undesirable constituents therefrom. To insure a sufiiciency of valid analytical data, test smoking requires a large number of cigarette smokings, smokings occurring under substantially the same conditions. Furthermore, the test procedures must approximate the conditions of human smoking. Human or mouth puffing does not provide acceptable test results because the character of one puff can not be reproduced exactly in the next puff. Furthermore, it is impractical and not economically feasible to use human smoking as the means for producing test data in the quantum required for testing practices prevalent in the present day tobacco industry. Thus controlled mechanical pufling of the cigarettes is employed. In conjunction with the mechanical test smoking technique, certain test criteria are established. In this manner, the testing occurs under uniform conditions contributing to more accurate compilation of test data. Thus, for example, the duration of puff can be accurately controlled to last exactly two seconds, the volume of each puff from a cigarette the same, and the frequency of putts the same for all tests. These criteria are duplicated uniformly mechanically with the smoking machine of the present invention which is characterized by its simplicity of construction, reliability of operation for meetatent ice ing the prescribed criteria and adaptability for use with a variety of analyzing devices.

Other objects of the present invention will in part be obvious and will in part appear hereinafter.

Summary of the invention In general, the smoking machine of the present invention comprises a positive displacement, reciprocating type pump unit which is driven by a variable speed drive motor coupled with the pump piston by means of a rack and pinion drive. The arrangement includes suitable frame means supporting the drive motor for bodily reciprocating travel during the stroking of the pump. Control means are provided to operate the pump one cycle during a given time period, as for example, one minute to correspond with the average puffing interval associated with human smoking. 'During the pump intake stroke, a predetermined quantity of smoke is puffed from the cigarette and on the discharge stroke is expelled from the pump to a testing unit, as for example, a gas chromatograph. A suitable valving means in the form of a multi-port solenoid valve is provided to control flow to and from the pump, the closure condition of the respective valve ports being controlled by switching trneans operating in correspondence to the stroking action of the pump unit. By employing suitable control circuitry, the drive motor speed may be varied to stroke the piston at a slower lineal speed during the pump discharge stroke than that applicable during the intake stroke.

According to the invention, a damping means can be provided to cushion the inertia of the motor assembly during the pump discharge stroke to prevent possible damage to the drive gears and pump parts. This is of particular importance where the smoke puffed from the cigarette is to be delivered by the pump to a testing device maintained under an evacuated state.

The invention accordingly comprises the features of construction, combination of elements, and arrangement of parts, which will be exemplified in the construction hereinafter set forth and the scope of the invention will be indicated in the claims.

Brief description of the drawings For a fuller understanding of the nature and objects of the invention, reference should be had to the following detailed description taken in conjunction with the accompanying drawings, in which:

FIGURE 1 is a perspective view of a smoking machine constructed in accordance with the principles of the present invention, some parts of the puifing unit being broken away for purposes of clarity and a control unit being shown located adjacent the puffing unit.

FIGURE 2 is a wiring diagram of the circuitry associated with the smoking machine shown in FIGURE 1.

Throughout the description like reference numerals are used to depict like parts in the drawings.

Description of the preferred embodiments The smoking machine of the present invention will be described herein in representative embodiment form as being utilized for test smoking one cigarette at a time with the smoke puffed from the latter being delivered to a gas chromatograph for analysis. However, those skilled in the art readily will appreciate that the machine has a wide range of application as for example, being used for smoking a plurality of ciragettes, being used in conjunction with other test analyzers, including spectrograph units, electrostatic precipitator units, etc., and for testing gaseous media other than cigarette smoke.

As seen in FIGURE 1, the smoking machine is a compact device having relatively few parts and the components thereof are conveniently mounted on a table, bench or wall surface 5 adjacent the test analyzer with which it is to be used. The latter analyzer is not shown in the drawings but it will be understood that the gas chromatograph referred to by way of example is a device well known in the art for analyzing the solids constituents of cigarette smoke by means of gas chromatography. The chromatograph unit also includes a recorder section wherein the analysis of smoke entering the unit is graphically recorded. The smoking machine preferably includes a base plate on which is supported the respective components to be shortly described in detail and which include a reciprocating positive displacement pump unit 11 provided for the purpose of pufling cigarette 12 at regular intervals. The pump unit includes the usual cylinder 14 supported parallel spaced from the base plate in a pair of spaced apart upright plate members 16 and 18 as shown in FIGURE 1, with the plate members 16, 18 being connected with the base plate 10 in a secure manner as by welding. Suitable tie rod members 20 also can be employed to hold the plate members apart at a fixed distance. A preferred form of pump unit is one wherein both the cylinder 14 and piston 22 are made of glass, the head 24 of the piston having a suitable seal ring of elastic material extending therearound as at 26 to properly seal the displacement volume of the pump unit from the atmosphere during operation. An advantage of utilizing a glass pump unit is that the outer top surface of the cylinder 14 can be marked with graduations 28 denoting the volume displaced for a corresponding length of pump stroke. The graduations 28 may be arranged in terms of cubic centimeters of piston displacement inasmuch as standards employed in the tobacco industry usually involve puffing volumes of cigarette smoke and/ or air up to 100 cubic centimeters per puff. In this manner visual determination of the pufiing volume of the pump during operation is possible and facilitates adjusting the pump pufiing volume in the manner to be described later in the specification.

The drive with which the pump piston is reciprocated will now be described. The drive includes a toothed rack 30 mounted on the base plate and extending longitudinally in the same direction as the pump cylinder 14, the axes of the cylinder 14 and rack 30 both being in the same plane extending perpendicular to the plane of the base plate 10. The outer end of pump piston 22 has a section of reduced diameter as at 21 and on which is formed a pair of concentric flanges 32, 34 between which engages the upstanding web 36 of a specially shaped coupling bracket 38, the web 36 being notched as at 37 to fit snugly against the piston surface between the flanges. Integral with web 36 and extending forwardly therefrom is an upper bracket segment 40 which in turn is connected with a parallel spaced lower bracket segment 42 by means of an integral vertical web segment 44, the segments 40, 42, 44 essentially comprising a structure of channel section. It will be apparent that the coupling bracket can be shaped from a flat plate, cast as a unit or formed in any suitable manner as would occur to those skilled in the art. The coupling bracket 38 is supported in and bodily reciprocates along parallel spaced guide tracks during operation of the pump unit, with the guide tracks being secured to base plate 10 in known manner. As will appear, the coupling bracket during its sliding travel passes unobstructedly over the toothed rack 30.

The drive for reciprocating the pump piston 22 is provided by way of a reversible, variable speed electric motor 54, the output shaft of which is connected by means of a slip clutch 56 wtih a pinion shaft 58, with the latter extending between coupling bracket Web segments 40, 42 as shown and carrying a pinion gear 60, the pinion gear being in mesh with the toothed rack 30. Pinion shaft 58 is supported on bracket segment 42 as by means of bearing straps 64 with the lower bracket segment being correspondingly grooved it) provide bearing surfaces in which the pinion shaft rotates. To provide clearance for the pinion gear to rotate within the coupling bracket, the lower bracket segment 42 is slotted as at 55. It will be apparent that when the drive motor 54 rotates in a given direction, the pinion gear 60 will move bodily longitudinally along the toothed rack in a corresponding direction carrying with it the motor 54, coupling bracket 38 and the pump piston coupled to the latter. The stroking of the pump thus is controlled by the direction and duration of rotation of the drive motor, these controls operating as will appear later in the description according to the intended test conditions. During stroking, the drive motor 54 which reciprocates bodily in a direction parallel to the toothed rack 30 can be supported on suitable guide rails 61 to avoid bending reactions at the coupling bracket 38.

The stroke of the pump piston 22 and hence the volume puffed may be varied depending on the application to which the pufling unit is put for test smoking purposes. Moreover, the puff duration may be set to last for a given time period. The piston stroke length and puff time thus determine the speed at which drive motor 54 must rotate, which speed is controlled by a suitable setting of control unit which unit shall be described more fully later in the description. At the end of the respective pump strokes, power to the drive motor 54 is interrupted and the motor stops. However, the circuitry controlling motor operation is designed to provide means for manually and automatically reversing the direction of motor rotation at the end of each stroke. Shutdown of the drive motor at the end of the pump intake stroke of the pufling cycle is effected by means of the control circuitry including a mechanical stop in the form of a limit switch unit 66. Limit switch unit 66 may be supported in a suitable housing 68 with the latter being adjustably secured to the base plate 10, as for example, by means of bolt fasteners passing through the housing and slidably moveable in slits 70 formed in the base plate 10, the bolts being tightened to fix the housing. Depending on the location of limit switch unit 66, the pump unit will pufi varying amounts of smoke or smoke admixed with air, as for example, 35 cc., 50 cc. or 100 cc. A limit switch unit 72 similarly is provided to shutdown the drive motor at the end of the pump discharge stroke, the limit switch unit 72 being fixed to the base plate 10 at a location suited to cause, at the end of the pump piston discharge stroke travel, actuation of the limit switch by a striker arm bracket 80 moving in tandem motion with that of the piston 22 and the function and structure of which will be made apparent later in the description.

During each puffing cycle, i.e., one complete intake and discharge stroke of the pump piston 22, fiow to and from the pump cylinder 14 is controlled by means of a solenoid valve 84. The solenoid valve essentially is a multi-ported valve device the operation thereof being controlled according to the direction of rotation of drive motor 54 to place the pump cylinder 14 in communication with the cigarette 12 and test analyzer, respectively, during the intake and discharge strokes of the pumping cycle. The solenoid valve body is provided with a number of conduits or tubes extending exteriorly thereof. One tube connects the solenoid valve with the pump cylinder, another tube 112 connects the valve with a filter assembly 114 in which is inserted the cigarette 12 being puffed and a third tube 118 is utilized for admixing air with the smoke drawn into the pump cylinder. A tube 120 connects the solenoid valve with the test unit-the gas chromatograph. It may be advantageous in delivering the smoke puffed from the cigarette to the gas chromatograph to maintain the latter device under a semi-vacuous condition to facilitate full discharge of the smoke in the pump cylinder to the test device. With the smoke train open to a semi-vacuous condition, the pressure of the atmosphere will act on the pump piston 22 in such manner as to ac celerate its speed of travel during the discharge stroke beyond that attributable to motor drive. The inertia which builds up during the piston return stroke could have serious damaging effects on the pump piston, pump cylinder, pinion gear and drive motor when these stiuctures come to an abrupt halt at the end of the pump discharge stroke unless this inertia is dissipated by means of the damping unit now to be described.

The damping unit shown generally at 130 includes a cylinder 132, a piston 134 slidable in the cylinder, a coupling bracket 136 connected to the piston rod 134a, and striker arm bracket 80 which connects the coupling bracket 136 with drive motor 54. Thus damping piston 134 moves with a reciprocating motion the same as that of piston 22 of the smoke puffing pump unit. The damping unit also includes a pressure relief chamber 142 into which oil is discharged from cylinder 132 during the discharge stroke of the pufiing unit, a needle valve 144, a one-way check valve 146 and tubing 148, 150 associated with each valve and connected with the relief chamber 142. As will be noted from FIGURE 1, oil in the damping unit system upon intake stroking of the puffing unit pump will be drawn into cylinder 132 from relief chamber 142 by way of tubing 150 and one-way check valve 146. At the end of the pulling unit intake stroke, cylinder 132 is filled with oil so that as the pulling unit commences its discharge stroke in an opposite direction, the piston will expel the oil from cylinder 132 to the relief chamber. However, outflow of oil from the cylinder has to be by way of needle valve 144 and tubing 148 to the relief chamber since check valve 146 prevents flow therethrough during puffing unit discharge. The oil in passing through the constricted passage of needle valve 144 dissipates the inertia of the pufiing unit by transforming same to fluid friction. This retards the movement of the pufiing unit sufiiciently to limit its speed to that produced by the drive motor 54. Thus, for example, the discharge stroke of the pumng unit pump piston may be set according to test procedure to last four seconds. On the other hand, if the smoke being discharged therefrom is directed to an analyzer maintained under vacuum, the efiect would be to stroke the pump in discharge at a runaway condition in only a fraction of the intended stroke time possibly causing damage to the pinion gear 60, rack 31) or other part in the drive system.

The control unit 100 shown mounted adjacent the pufiing unit in FIGURE 1 includes a housing in which is located the devices comprising the circuit shown in FIGURE 2 as well as the timer unit 190. At the top side of the housing there is provided a push button 242 connected with the controlling operation of momentary control switch 160, a control knob 244 for adjusting the setting of variable resistor 180, a control knob 246 for adjusting the setting of variable inductor L1, a control knob 247 for controlling a main power off-on switch 400 connected to an A.C. power source, a control knob 248 for controlling switch 172 and a control knob 250 for controlling ganged switche 182, 183.

Control knob 247 is adapted to connect the control unit with an A.C. power source regardless of whether the pufling unit be operated in manual or automatic mode. It will be apparent that moving control knob 247 to the on position will energize at all times timer unit 190, although the latter will not be effective to control automatic circuit operation unless and until control knob 250 is also moved to an on position. When operating the smoking unit in manual control, control knob 248 is moved to an on position to close switch 172 thereby energizing the control unit for operation under the direction of momentary control switch 160 whereas moving control knob 250 to on position closes ganged switches 182 and 183 and the puffing unit will start Operating in automatic control immediately. Control knob 246 is used to adjust the setting of variable inductor L1 and control the input to transformer L2 and consequently the DC. output voltage of full wave rectifier unit 174. The speed of drive motor 54 thus is a function of this D.C. voltage and the latter is set at a value requisite for stroking the pump piston a distance corresponding to the volume to be puffed in a given time period. For example, if the intake stroke length corresponding to 35 cc. is 3 inches and the puffing period 2 seconds, the inductor L1 is set to give a motor speed capable of driving the pinion 30 at a lineal speed of 1.5 inches/ second. In addition to this provision for overall control of motor speed, means are provided for reducing the motor speed during discharge. Thus, if it is required as part of the testing procedure to discharge over a greater discharge stroking time than 2 seconds, the setting of control knob 244 is adjusted accordingly to change the effective value of the variable resistor 180 in the control circuit. For example, if the discharge stroke is to take 4 seconds, the resistor 180 is set to reduce the DC. voltage to the drive motor by one-half, and hence its r.p.m. by one-half as compared with the intake stroke speed. Thus the lineal speed of pinion 30 during the discharge stroke is only .75 inch per second.

The smoke train of the pufling unit includes a filter unit 114 in which the cigarette 12 is supported during smoking. The filter unit 114 is a type well known in the art commonly referred to as a Cambridge filter and for that reason is not depicted in detail in the drawings. The filter unit includes two interfitting plastic parts which screw together with an air-tight fit and are designed to house a filter disc of an absorbent material with which the smoke is filtered and certain solids constituents thereof removed from the smoke. In the particular embodiment described herein a filter disc is not employed since as the test involves a gas chromatograph analysis, the smoke solids analyzed should be those present in the smoke as it leaves the cigarette. The Cambridge filter structure less the filter disc, is used however as a cigarette holder for reasons of convenience and because it includes a rubber seal means adjacent the cigarette receiving aperture therein which tightly engages the periphery of the cigarette to prevent spurious aspiration of air into the smoke train around the outside of the cigarette during puffing. The Cambridge filter is connected with the multi-port solenoid valve 84 by means of tube 112, the solenoid valve in turn being connected with the pump cylinder 14 by means of the tube 110. The solenoid valve 84 is also a device of known construction and has a number of ports therein which can be opened and closed according to predetermined sequence upon energization of solenoid means therein associated with each port. The energization function is controlled by circuitry within the control unit in conjunction with the direction of rotation of drive motor 54 and will be described in more detail later on in the course of the description. The structure and operation of the smoke train is relatively simple but yet effective for the intended purpose. It can be best understood by reference to the following description of the events transpiring during one puffing cycle. At time zero in any pufiing cycle, that is, at the start at the intake stroke of the pump unit 11, the solenoid valve port controlling flow from the pump to the testing device is in a closed condition. On the other hand, the valve port which communicates with tube 112 and hence the cigarette 12 is open. Thus, during the pump intake stroke, smoke will be drawn from the cigarette through the solenoid valve and into the pump cylinder 14. At theend of the intake stroke, that is, after 35 cc. of smoke has been drawn into the pump cylinder (two seconds from the time zero), the valve port connected with tube 112 closes automatically. As the pump unit drive reverses direction to initiate the discharge stroke, the port controlling flow from the pump cylinder to the test analyzer opens to permit delivery of the smoke to the testing unit. In certain test smoking procedures, air may be mixed with the smoke puffed from the cigarette to facilitate the delivery of the smoke to the testing unit and to dilute the smoke concentration so as to prevent the recording needle in the gas chromatograph from running off the recorder. If the latter procedure is employed, the air may be admixed in one of several ways. This of course will involve the piston 22 stroking a greater distance on intake so that after pufiing 35 cc. of smoke the pump unit may be arranged by suitable adjustment of limit switch unit 66, to continue to stroke in the intake direction for an additional time period during which the valve port which controls flow between the cigarette and pump cylinder is closed whereas a third port used for controlling flow between the pump cylinder and the atmosphere is opened to allow an amount of air as for example 35 cc. to be drawn into the pump cylinder. When the pump starts its discharge stroke, only the port controlling flow to the testing unit is opened while the others are closed. In the instance where it is desired to mix air with the smoke on intake, the cut-off of smoke draw at 35 cc. may be effected by means of a switch controlling the solenoid associated with the appropriate atmosphere port. In one embodiment, the switch which is a two position type 300 may be mounted on one of the guide rails 50 in which coupling bracket 38 slides so that at the point when the leading edge 44- of the coupling bracket 38 reaches a travel distance corresponding to a 35 cc. puffing volume, the switch closes thereby energizing the atmosphere port solenoid to open same. It will be apparent that if the smoking machine is provided with means for admixing air with the smoke puffed, and it is used for a test involving only an intake of 35 cc. of smoke, the limit switch unit 66 should be set to be struck by coupling bracket 38 at the same time the latter makes contact with the switch 300.

A better understanding of the smoking unit will be apparent from the following description taken with reference to FIGURE 2 wherein is illustrated the control circuitry for controlling the operation of the pufiing unit drive motor 54 and smoke train devices. The purpose of the circuitry is to provide a single stroking of the pump piston 22 from one mechanical stop (limit switch 66) to another (limit switch 72) upon a control demand initiated either manually through operation of the momentary control switch 160 or automatically through triggering signals applied to the circuit from terminals 161 and 162 of a timer device 190. In describing first the manner of manual circuit operation, it will be noted that the control circuit comprises drive motor 54, limit switches 66 and 72, motor drive relays 164 and 166 controlled respectively by the limit switch units 66 and 72, a full-wave rectifier 174, a polarity-reversing relay 170 and momentary control switch 160. AC. power is supplied through power switch 172 and variable inductor L1 to the primary winding of transformer L2. The secondary winding of transformer L2 is connected with full wave rectifier 174 which in turn provides a source of D.C. voltage variable in magnitude between to 35 volts for operating drive motor 54. This D.C. voltage, which is varied in magnitude according to the setting of inductor L1 is applied through relay 170 to selectively drive motor 54. Energizing power for relays 164 and 166 is supplied from the A.C. power main through power switch 172 and limit switches 66 and 72 respectively.

In the position shown in FIGURE 2, the control circuit is operative and the pump piston 22 is at about midpoint in its intake stroke traveling from right to left. At this point in time relays 170 and 166 are unenergized whereas relay 164 is energized through the closed contacts 66a and 172a. Motor terminal 54a is connected through contact 1700 to terminal 174a of the rectifier circuit. Motor terminal 54b on the other hand is at this time connected to terminal 17 419 of the bridge circuit through relay contacts 166a, 164a and 170a. Thus, a first polarity of interconnection between drive motor 54 and rectifier 174 exists and the motor is driven so as to direct the piston 22 from right to left. As the left-hand mechanical stop is approached, contact 66a is opened by engagement of coupling bracket 38 with limit switch 66 whereupon relay 164 is deenergized. This opens the circuit between motor terminal 541) and rectifier terminal 174b, removing D.C. power from drive motor 54. Shortly thereafter contact 66b is closed whereupon relay 170 is energized and terminal 17% of the bridge circuit becomes connected through variable resistor 180 and contact 170d to motor terminal 54a.

Terminal 174a of the bridge circuit also becomes connected with momentary control switch through contact 1701;. But since momentary control switch 160 is open, motor terminal 54b remains disconnected from D.C. power. The drive motor 54 remains stopped until momentary control switch 160 is depressed to initiate the discharge stroke of the pump piston. When the momentary control switch is operated, continuity between terminal 174a of the bridge circuit and motor terminal 541) is established. A second (reverse) polarity of interconnection now exists between drive motor 54 and rectifier 174 and the motor 54 will rotate in the appropriate opposite direction to drive the pump piston from left to right. As the drive motor displaces the piston 22 rightward, contact 66b is caused to open and contact 66a to close. The opening of contact 661) has no effect upon the state of relay since a holding circuit is provided for this relay through contact 170i and contact 720. Closure of contact 66a energizes relay 164 which has the effect of providing a path of continuity around momentary control switch 160 to motor terminal 54b. The path comprises relay contacts 164a, 166a and motor terminal 54b. Thus, despite the fact that momentary control switch 160 is now open and contact 66b is also open, D.C. power is provided to drive motor 54 to stroke pump piston 22 rightwardly. As the piston approaches the right-hand limit switch unit 72, contact 72a is opened and the holding circuit for relay 170 is interrupted and the relay is deenergized. Momentarily thereafter contact 72b is closed, energizing relay 166 and interrupting the D.C. power to motor terminal 541). Thus, the drive motor 54 stops and the potential applied to the terminals thereof is reversed by the change in state of relay 170. Again, the system Will remain at rest until the momentary control switch 160 is again depressed to initiate the next intake stroke. As the momentary control switch 160 is depressed, power to the drive motor 54 is momentarily applied through switch 160 from contact 170a and the motor commences its leftward drive, contact 72b is opened, deenergizing relay 166 which provides again the alternate power path to motor terminal 54b through the above mentioned circuit comprising contacts 164a, 166a and motor terminal 54b. The closure of contact 72a caused by the leftward movement of the piston has no effect on system performance at this time since the holding circuit contact 170 is in its normally open state. The circuitry described to this point is then a manually triggered arrangement for providing a single displacement of the pump piston from one limit switch position to the other. It should be noted that resistance is made variable to provide a different (slower) piston speed of the pump piston during the discharge stroke.

The function of momentary control switch 160' is accomplished in the automatic mode by means of a timer unit 190. The timer unit is a device of known construction adapted to initiate operation of the puffing unit according to a predetermined cyclic frequency. For example, the timer is adapted to supply a signal which will stroke the pump unit one pumping cycle per unit of time, as for example, one puff/minute. In the automatic mode, switch 172 providing manual mode power is open and momentary control switch 160 is not employed. Ganged switches 182 and 183 on the other hand are closed by moving control knob 250 to an on position and the variable inductor L1 becomes connected to power main terminals 190a and 19% contained within the tim ing device. The method of operation of the system is the same as described above with the exception that the switching function of momentary control switch 160 is accomplished by a switch means (not shown) within the timer connected to terminals 161 and 162. This timer switch is in parallel with momentary control switch 160, being connected from terminal 161 directly to the junc tion of switch 160 and motor terminal 54b and from terminal 162 to the other terminal of the switch 160'. By the controlled closure and opening of this timer switch by a cam or like device, reciprocation of the plunger from one stop to the other may be controlled according to any desired periodicity.

In conjunction with the stroking of pump piston 22, the solenoid valve 84 is operated to close and open the ports therein according to the demands of the smoking train. This control is effected in the manner now to be described. During the intake stroke of the pufiing unit, the pump cylinder 14 communicates with the cigarette 12 by means of the appropriate valve port X which should be open during that time, with the opening of said valve port being controlled according to the direction of rotation of drive motor 54. Thus, during the intake stroke, terminal 54a of the motor is connected with the positive terminal 1740 of the D.C. power source and the contact 170p of relay 170 is used to supply current through switch 300, which is in the left-hand contact position shown in FIGURE 2 during intake, to the solenoid closure member 301 controlling the port X connecting the cigarette with the pump cylinder. During the time that drive motor 54 is rotating to drive the piston in an intake direction the said solenoid is energized and its associated port will re- ,main open and only smoke will be drawn into the pump cylinder 14. If the arrangement is such that only 35 cc. of smoke is to be drawn in during intake, at that point the motor direction will be reversed by limit switch unit 66 as described before. In that event, the contact 170p opens and contact 170r closes. This then completes a circuit from terminal 174a through contact 170r to the solenoid closure member 305 controlling the port Y in the solenoid valve which places the pump cylinder in communication with the test analyzer unit and smoke is thereby directed from the pump to the analyzer unit during the discharge stroke. As was previously mentioned in the description, it is advantageous at times to admix air during the intake stroke for the reasons previously discussed. If such procedure is to be followed during the intake stroke, the coupling bracket 38 will strike the actuator of switch 300 positioned on the guide rail 50 and will move the switch 300 from the left-hand contact position shown in FIGURE 2 to the right-hand contact position against contact 306 which thereby completes a circuit connecting terminal 174a of the D.C. power source to the solenoid closure member 303 controlling the valve port Z which connects the pump cylinder to atmosphere by way of tube 118. Simultaneous with the change of position of switch 300, solenoid closure member 301 is deenergized and its associated port X closes so that no additional smoke can be drawn into the cylinder from the cigarette. The actuation of switch 300 is designed to occur as soon as the pump piston 22 is stroked a distance corresponding to 35 cc. of displacement and the switch actuator is mounted on guide rail 50 accordingly. The switch 300 remains in the right-hand position against contact 306 until the end of the intake stroke as for example, after 35 cc. of air has been drawn in and mixed with the 35 cc. of smoke already in the cylinder. Upon the initiation of discharge, solenoid closure member 305 will be energized as previously described and although circuit continuity to solenoid closure member 303 is maintained through switch 300 initially in the pump discharge stroke, the contact 170p is now open and the atmosphere port Z will close and stay closed. During the course of the pump discharge stroke, the coupling bracket 38 will pass beyond the switch 300 in guide rail 50 and the switch will once again return to the left-hand contact po- 10 sition of FIGURE 2 reorienting this switch for control of the smoke intake port X during the next putiing cycle.

While there is disclosed but one embodiment of the smoking unit of the present invention, it is possible to produce still other embodiments without departing from the scope of the inventive concept herein disclosed, and accordingly it should be understood that all matter contained in the above description and in the accompanying drawing should be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. A smoking machine for puffing smoke from a cigarette and delivering same to a smoke analyzer unit com prising.

a holder for holding the cigarette to be smoked,

a pump unit for puffing the cigarette comprising a cylinder, and a piston slideable in said cylinder,

a smoke train connected with said pump unit including a control valve, a first conduit connecting said control valve with said cylinder, a second conduit connecting said control valve with said holder, and a third conduit connected with said control valve for delivering smoke to said smoke analyzer unit, said control valve being operable to selectively interconnect each of said conduits with at least one other of said conduits,

a drive unit for reciprocating said piston including a toothed rack extending longitudinally of said pump cylinder, a pinion gear in mesh with said toothed rack, a reversible electric drive motor connected to said pinion gear for rotating same, means for supporting said pinion gear and said reversible drive means for bodily movement longitudinally of said toothed rack as said pinion gear rotates, said support means being coupled with said piston,

means for controlling the operation of said drive motor comprising a circuit including a source of power for operating said motor, switch means for connecting said drive motor with said source of power in one condition of polarity for rotating said motor in one direction whereby said piston is stroked in an intake direction, and additional switch means operable to connect said drive motor with said source of power in an opposite condition of polarity for rotating said motor in an opposite direction whereby said piston is stroked in a discharge direction, and

valve control means operable during at least a portion of the time said motor is rotated in said one direction for orienting said control valve to interconnect said first conduit with said third conduit, and to interconnect said first conduit with said second conduit when said motor is rotated in said opposite direction.

2. The smoking machine of claim 1 wherein said control valve includes ports associated with each of the respective conduits, and separate solenoid members controlling the closure condition of each port, said control means being operable responsively to the direction of rotation of said drive motor for energizing said solenoid members.

3. The smoking machine of claim 1 wherein the means for controlling the operation of said reversible drive motor includes a device connected with said power source for varying the magnitude of the output of the latter whereby the speed at which said drive motor rotates said pinion gear is correspondingly varied.

4. The smoking machine of claim 1 wherein said circuit controlling the operation of said reversible drive motor includes means for operating said drive motor at a slower speed in said opposite direction than the speed at which said drive motor operates in said one direction.

5. The smoking machine of claim 4 wherein said means for operating said drive motor at a slower speed comprises a resistor in circuit with said power source and said drive motor and elfective only during the time said drive motor is operated in said opposite direction.

6. The smoking machine of claim 1 wherein said smoke train includes a fourth conduit connecting said control valve with atmosphere, the control means operable responsively to the direction of rotation of said drive motor for orienting said control valve including a device eifective to disconnect communication between said first and third conduits and interconnect said fourth conduit with said first conduit after said pum piston has travelled a predetermined distance during the intake stroke thereof.

7. The smoking machine of claim 1 wherein the circuit controlling the operation of said reversible drive motor includes a first limit switch unit operable to interrupt power to said drive motor at the end of the piston intake smoke, and a second limit switch unit operable to interrupt power to said drive motor at the end of the piston discharge smoke.

8. The smoking machine according to claim 1 wherein the circuit for controlling the operation of said drive motor includes a momentary control switch for manually connecting said power source with said drive motor, and a timer unit adapted to connect said drive motor with said power source automatically with cyclic periodicity.

9. The smoking machine according to claim 1 wherein the means for supporting said pinion gear and drive motor for bodily movement longitudinally of said rack comprises a pair of guide rails arranged one at each side of said toothed rack and extending parallel thereto, a coupling bracket slideable on said guide rails, a shaft rotatably supported in said coupling bracket, said pinion gear being carried on said shaft, said drive motor being connected with said shaft, said coupling bracket having a web portion thereon connected with said piston.

10. The smoking machine of claim 1 further comprisa hydraulic damping unit operatively coupled with said pump piston and effective to dissipate mechanical inertia created in said pump piston during the discharge stroke thereof.

11. The smoking machine according of claim 10 wherein said hydraulic damping unit includes:

a cylinder, and

a piston slideable and said cylinder, said damping unit piston being coupled with said pump piston to move in tandem with the movements thereof.

References Cited UNITED STATES PATENTS 2,228,216 1/1941 Morgan 73-23 RICHARD C. QUEISSER, Primary Examiner JOHN K. LUNSFORD, Assistant Examiner US. Cl. X.R. 7328 

